Last month, Elton John sought an injunction to prevent a photograph of him taken in the street being published in a newspaper. The picture simply showed him casually dressed but he complained that it showed that his baldness was returning and was an invasion of his privacy. He failed to obtain the injunction, but his case highlights the gap between privacy law as it currently stands in the UK and as it is apparently required to be under the European convention on human rights.

Two years ago, the House of Lords, the highest domestic court, held that the privacy of supermodel Naomi Campbell had been invaded when a picture of her leaving a Narcotics Anonymous session was published. However, their Lordships were careful to circumscribe the developing law of privacy, stating that it did not apply, in the homely words of Baroness Hale, to pictures of someone "popping out to buy a pint of milk". To infringe the right to privacy, the photo had to show some intimate detail of the person concerned.

However, about a month later, the European court of human rights in Strasbourg held that the publication in the media of any picture of Princess Caroline of Monaco infringed her right to privacy under article 8 of the convention regardless of whether it showed anything that could be considered intimate.

Ever since, media lawyers have been mulling over how to reconcile these two decisions. One view is that although on the face of it, the Princess Caroline decision appears to confer a right to privacy to restrain the publication of any picture of an individual - unless it could be said to serve some pubic interest - it in fact relates more to the harassment of repeatedly being photographed in public over many years. But this is controversial.

The Elton John application was the first time since these two decisions were handed down that a case was brought that illustrated the difference between them. There was nothing inherently private about the photograph - it was closely akin to "popping out to buy a pint of milk", the express exception identified by Baroness Hale. On the other hand, on a strict reading of the Princess Caroline decision, this appeared to be a breach of article 8.

The House of Lords has recently stated that where there appears to be an inconsistency between decisions of a higher court in the UK and of the Strasbourg court, the rule of precedent applies. That is that the court must follow the domestic decision even if this seems to be at odds with the European court. While the lower courts must have regard to decisions from Europe they must also apply precedent strictly from a superior court in the UK.

This is what Mr Justice Eady chose to do on Elton John's application, holding that there was no invasion of privacy based on the Lords' Campbell judgment.

The difficulty is that this is arguably inconsistent with the European court, and if such a case were to proceed again to the House of Lords it is quite possible that their Lordships might come up with a new formulation for domestic privacy law more in line with the Princess Caroline decision, not least because if they did not, it might leave the UK vulnerable to an action before the Strasbourg court for failing to implement the convention properly.

However, until such a case is brought to the Lords, the lower courts must slavishly follow the decision in Campbell, with its narrower interpretation of privacy invasions. This leaves privacy law in the country - at least in this important aspect - hopelessly confused and uncertain.